Beneficiation of ores containing potassium chloride and magnesium sulfate



Patented Sept. 14, 1954 BENEFICIATION OF ORES CONTAINING POTASSIUM CHLORIDE AND MAGNE- SIUM SULFATE William B. Dancy, Carlsbad, N. Mex, assignor to International Minerals & Chemical Corporation, a corporation of New York No Drawing. Application March 18, 1952, Serial No. 277,293

7 Claims.

The present invention relates to a method for the control of glaserite formation in certain beneficiation processes. More particularly, it relates to a method for the control of glaserite formation in certain systems containing magnesium sulfate salts, sodium chloride, and potassium chloride.

Potassium containing ores of the type mined in the Carlsbad, New Mexico area, such of sylvinite, langbeinite, and mixed ores, i. e. sylvinite and langbeinite, contain sodium chloride, potassium chloride and magnesium sulfate double salts (KzSO4.2MgSO4). These ores are beneficiated in order to recover potassium and/or magnesium values therefrom by processes such as flotation, tabling and the like. In these beneficiation processes, ore particles are suspended in aqueous brines and the brines which are conventionally employed are substantially saturated with respect to sodium chloride and potassium chloride.

The pulp is introduced into the benefication system in which, for example, potassium chloride is separated by flotation, tabling or other methods.

The ores usually contain magnesium sulfate double salts, and pulping of the ore with the aqueous brine results in the solution of magnesium salts and the formation of glaserite. The glaserite crystallizes indiscriminately throughout the recovery system and causes pipe line and launder stoppage, thickener and classifier problems, and other operating difficulties which make it necessary to periodically interrupt the process to remove the glaserite which has deposited. It would be desirable if the glaserite formation in the pipes and at points which cause stoppages and other .operational difficulties could be controlled or eliminated.

It is an object of the instant invention to provide a method for the control of the formation of glaserite in certain beneficiation processes.

It is a further object of the instant invention to control the formation of glaserite in beneficiation processes in which ores containing magnesium sulfate double salts are pulped with brines substantially saturated with respect to sodium chloride and potassium chloride.

These and other objects of the instant inventio will become more apparent from the description of the process as herein set forth.

It has been discovered that the crystallization of glaserite can be controlled and the formation and build-up of glaserite deposits at undesirable points in beneficiation processes, in which aqueous brines which are substantially saturated with respect to sodium chloride'and potassium chloride are pulped with ores containig magnesium sulfate double salts, can be minimized by retention of the pulp in a preinixing tank or a container provided with means for mixing said ore pulp in order to allow glaserite to form and deposit prior to introducing the pulp into the beneficiation system.

In one embodiment of the instant invention, sylvinite ore which contains magnesium sulfate double salts is pulped with a brine which is substantially saturated with respect to sodium chloride and potassium chloride and is agitated by any convenient method, for example, in a tumbler. The pulp is retained in the tumbler until solution of the magnesium sulfate and formation of glaserite is substantially complete. Usually about ten minutes are sufficient when mixing is efficient. However, longer periods may be employed. When glaserite is allowed to crystallize in a preliminary mixing container or tank it will not crystallize at critical points in the recovery process as it does in conventional processes in which mixing of the brine and ore is rapid and no hold-up zone is employed prior to introduction of the pulp into the system. The glaserite which is formed in accordance with the instant process need not be separated from the pulp but can be introduced into the recovery system along with the pulp.

In one embodiment of the instant invention, sylvinite ore containing magnesium sulfate double salts is made into a pulp with brine substantially saturated with respect to sodium chloride and potassium chloride. The pulp has a solids density of between about 25% and about preferably between about 50% and about 65% solids. However, the density of solids in the mixture may vary as long as efficient mixing of the pulp is effected. The mixing may be carried out at any convenient temperature, preferably at about atmospheric temperature.

The formation of glaserite is accelerated if seed crystals of glaserite are present in the pulp mixture. For example, in the presence of glaserite seed crystals, most of the soluble magnesium sulfate crystallizes in the form of glaserite in a period between about ten and about fifteen minutes. Generally. between about two pounds and about twenty pounds of glaserite seed crystals are added for about a thousand pounds of ore, however,

larger or smaller quantities of seed may be employed. However, if no seed crystals are employed, the mixture should be agitated for longer periods, for example, between about one and about two hours prior to introduction into the recovery system. As previously stated, the gla- The'following examples are given in order to afford an illustration of the practice of the instant invention, but it is to be distinctly understood that the following examples are illustrative only and that there is no intention to limit the invention thereto.

EXAMPLE I About 5,000 grams of sylvinite ore containing magnesium sulfate double salts and about 5,000

grams of brine prepared by substantially saturating water with the sylvinite, were mixed. The resulting. mixture was. agitated' in a tumbler. Table 1 indicates. the relationship of the time of agitation to the percent. of. magnesium dissolved.

from the pulp brine which was. not. seeded with glaserite crystals.

Table I RELATIONSH'I'P'BETWEEN MIXING TIME AND PERCENT MAGNESIUM DISSOLVED Periodof Agitation. Dissolved,

minutes 30. 2 l2'minutes 37.8 24 minutes 43. 3 48 minutes 47. 8

Only about 50% of the magnesium in the ore will dissolve; Therefore, TableI indicates that after about forty-eight minutes solution of magnesium and the consequent formation of glaserite was substantially complete.

EXAMPLE II A pulp of. about 65% solids density was prepared, by mixing about 3,713 grams of sylvinite ore with about. 2,000- grams of the brine as described in Example. I. The resulting mixture was agitated. at room temperature in a tumbler.

Table II shows the relationship of. time and the percent magnesium. dissolved.

Table II SOLUTION OF MAGNESIUM FROM SYLVINITE PULPS Magnesium Time of Agitation Dissolved,

percent 5 minutes 34. 7 10 minutes .0. 43. 5 minutes 47. 6

This table indicates that the time necessary for the substantially completeformation of glaserite was decreased when'the solids density of the pulp was increased.

EXAMPLE III A pulp of about 65% solids was prepared as in Example II, and about 50 grams of glaserite seed was added to the pulp. The resulting mixture was agitated in a tumbler for about 10 minutes. The percent of magnesium dissolved was about Magnesium I percent 4 41.6%. The addition of seed minimizes supersaturation of the brine with respect to glaserite.

Having thus fully described the character of the instant invention, what is desired to be secured by Letters Patent is: l

1. In a process for the beneficiation of ores containing potassium chloride and magnesium sulfate to recover potassium chloride therefrom, the improvement comprising mixing said ore with brine substantially saturated with respect to potassium. chlorideand to sodium chloride, allowing the resulting pulp to stand until glaserite formation is substantiallycomplete, and introducing the resulting pulp into the system for the beneficiation ofsai'd oreto recover the potassium chloride therefrom.

In a process for the beneficiation of ores containing potassium chloride and magnesium sulfate to recover potassium chloride therefrom. the improvement comprising preparing a pulp of said ore with aqueous brine. substantially saturated with. respect to. potassium chloride and to sodium chloride, agitating the resulting pulp un til formation of glaserite is substantially complete, and introducing the resulting pulp into the beneficiation system for. the recovery of potassium chloride.

3. In a: process for the beneficiation of ores containing. potassium chloride and magnesium sulfate torecover potassium chloride therefrom, the improvement comprising preparing a pulp of said ore with sufiicient aqueous brine substantially saturated with. respect to. potassium chloride and to sodium chloride to obtain a slurry containing between about 25% and about 65% solids, agitating. the resulting pulp until formation of glaserite is substantially complete, and introduci'ng. the resulting pulp into the beneficiation system for the recovery of potassium chloride.

4.. In a process for the beneficiation of ores containing. potassium. chloride and magnesium sulfate to recover potassium chloride therefrom, the improvement comprising a pulp of said ore with brine which is substantially saturated with respect to potassium chloride and sodium chloride, adding. at least one glaserite seed crystal to the resulting pulp, agitating the seeded pulp for at least about ten minutes, and introducing the resulting pulp into a beneficiation system for the recovery of potassium chloride.

5. In a process for the beneficiation of sylvinite ores containing magnesium sulfate in which potassium chloride is recovered by a flotation process, the improvement comprising preparing a pulp of said ore with aqueous brine substantially saturated with. respect to sylvinite, agitating the resulting mixture at least until the formation of glaserite, is substantially complete, and introducing the resulting pulp into a froth flotation system for the recovery of potassium chloride.

6.. In a process'for. the beneficiation of sylvinite ores containing magnesium sulfate in which. potassium chloride is recovered by a froth flotation process, the improvement, comprising preparing a pulp of said ore with aqueous brine substantially saturated with respect to potassium chloride and to sodium chloride, adding at least one glaserite seed crystal to the. resulting pulp, agitating the resulting mixture for at least about ten min utes, and introducing the resulting pulp into a froth flotation system for the recovery of potas-- sium chloride.

7. In a process for the beneficiation of sylvinite ores containing magnesium sulfate and involving subjecting a pulp of said ore to a froth flotation process to recover potassium chloride therefrom,

I the'improvement comprising preparing a pulp of said ore with suflicient aqueous brine, which is substantially saturated with respect to potassium chloride and to sodium chloride, to obtain a slurry containing between about 25% and about 65% solids, adding between about two pounds and about twenty pounds of glaserite seed crystals per thousand pounds of ore to the resulting pulp, agitating the resulting seeded mixture for between about ten minutes and about sixty minutes, and subjecting the resulting pulp to froth flotation to recover potassium chloride therefrom.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Book Jan. 26, 1909 Howard Nov. 3, 1925 Ritchie et a1. Nov. 21, 1933 Martin May 15, 1934 Anderson Oct. 7, 1952 FOREIGN PATENTS Country Date Great'Britain Apr. 12, 1937 I Great Britain Mar. 12, 1948 

1. IN A PROCESS FOR THE BENEFICIATION OF ORES CONTAINING POTASSIUM CHLORIDE AND MAGNESIUM SULFATE TO RECOVER POTASSIUM CHLORIDE THEREFROM, THE IMPROVEMENT COMPRISING MIXING SAID ORE WITH BRINE SUBSTANTIALLY SATURATED WITH RESPECT TO POTASSIUM CHLORIDE AND TO SODIUM CHLORIDE, ALLOWING THE RESULTING PULP TO STAND UNTIL GLASERITE FORMATION IS SUBSTANTIALLY COMPLETE, AND INTRODUCING THE RESULTING PULP INTO THE SYSTEM FOR THE BENEFICIATION OF SAID ORE TO RECOVER THE POTASSIUM CHLORIDE THEREFROM. 